Adding additional current sensors to DRV8301 kit

in phase current sense will make a difference for your low inductance motors

on DRV8301 EVM only ADC-A4 is an open channel.

you could use B0 which is connected to the pot, or cut any of the other lines you aren't using.

Thanks.

I'm going to use A2,B2 (I_total,VDCbus). just take out the resistors from the board and connect to these channels through the breakout - J5.

As current sensor I'm going to use ACS759, +-50A,+-100A.

Two additional questions:

1. what is the preferred installation-

a. Place the sensor close to the phase output from the PCB - that means short wires to the motor, long wire to the J5 (ADC).

b. Place the sensor near J5 - long wire to the motor, very short to J5.

I would think (b). what do you think ?

2. The sensor does not use all 3.3V scale. in the datasheet they are giving the scale factor mV/A. How do incorporate this into motorware ? the pu values are not calculated as before... maybe to rescale in software to 3.3V, then use the usual pu transformation ?

thanks

1. I would place the sensor closer to the phase wires.

2. you need to scale the output of the sensor to 0-3.3V to maximize ADC resolution and allow the variables/software to be simpler.

 

 

Thanks Chris.

I read in some thread that the Vdc-bus is not important to FAST, and is used only for gain resetting.

Since I'm going to disconnect the Vdc-bus sampling in the 8301 EVM, just to be sure - FAST can function without any reading from the Vdc-bus ?When calling EST_run instead of the sampling information can I just place a constant, e.g zero ?

Thanks

you should place a constat equal to your expected Vbus in the pAdcData structure where Vbus is expected, by updating this in the HAL_readAdc  function

 

I think there should be some pu value in pAdcData.dcbus ?

should it be scaled with voltage_sf, as:

pAdcData.dcbus = _IQ(28.0) * votlage_sf;

where 28 is my expected dc voltage

?

Hi Chris,

when using 2 current sensors, then only :

pAdcData->I.value[0]

pAdcData->I.value[1]

are being used, so I don't need to set the

pAdcData->I.value[2]

right ?

I could do I.value[2]=-I.value[0]-I.value[1]

and then the regular 3 current sensors configuration... is there a benefit for that ?

Another issue is with the pu system - now I have :

USER_ADC_FULL_SCALE_CURRENT_A = 250.0

USER_IQ_FULL_SCALE_CURRENT_A = 130.0 A

and I get warning messages about overflow, I assume:

Description    Resource    Path    Location    Type
#175-D floating-point value does not fit in required integral type    proj_lab10a.c    ‪/RunControl‬    line 614    C/C++ Problem

For example:

// read Id and Iq vectors in amps
  gMotorVars.Id_A = _IQmpy(CTRL_getId_in_pu(ctrlHandle), _IQ(USER_IQ_FULL_SCALE_CURRENT_A));

so the above line will not work fine, I assume...

what to do ?

Thanks

the [2] value isn't used if you have (2) currrent sensors set in user.h, so it doesn't  matter what is in the structure.

 

yes on the data type...try this

// read Id and Iq vectors in K amps
  gMotorVars.Id_kA = _IQmpy(CTRL_getId_in_pu(ctrlHandle), _IQ(USER_IQ_FULL_SCALE_CURRENT_A / 1000.0));

Hello Chris

I have the same issue with my high current ACIM. 

USER_IQ_FULL_SCALE_CURRENT_A = 250;

#define USER_MOTOR_MAX_CURRENT          (140.0)

But I can not even find the "gMotorVars.Id_A" in lab12b. Why?

I'm so confused about how to modify the code when I use the high current motor. Can this work only by modify the gMotorVars.Id_A without modifying any other code? 

gMotorVars.Id_A is just a display variable for the current in Id. It is nothing to modify.
in your case you are measuring +/- 125 A, yet you set a peak Iq current of 140A. This isn't advisable.

gMotorVars.Id_A is only in proj_lab10. If you want this in your proj_lab12, view how this is don't in proj_lab10 and add to your code.

Hi,

i'm going to use in-phase current sense for DRV8301-69M KIT and have a question to your application:

" I'm going to use A2,B2 (I_total,VDCbus). just take out the resistors from the board and connect to these channels through the breakout - J5."

--> what resistors do i need to take out ? do you have PCB description or layout? E.g using A2, i would connect external sensor to pin 33 of J5. But where is pin 33 of J5 since there are no hint about the pin number of J5.

--> did the change using in phase current sense work well? or does anyone have experience with this issue?

regards,

Giang